Means for reproducing sound from photographic records



May 9, 1933. F. DEANE 1,907,748

MEANS FOR REPRODUCING SOUND FROM PHOTOGRAPHIC RECORDS Filed Dec. 7, 1932 840mm fame auze.

per (4 H 2 hmne y.

Patented May 9, 1933 FRANCIS DEANE, OF FOLLOWFIELD, ENGLAND MEANS FOR REPRODUCING SOUND FROM PHOTOGRAPH'IC RECORDS Application filed December 7, 1932, Serial N 0. 646,147, and in Great Britain May 7, 1931.

the edge 4 so that the knife edge 4 divides the beam of light from a source 13 into two equal parts, the angles of incidence of these two beams being small and so directed that they are most effectively projected on to the cells 1 and 2. The usual supplementary slotted plate 14 can be located in front of The invention relates to improvements in and connected with the reproduction of sound intalking cinematography. It 18 known in this class of work to form on a film two separate sound tracks and to employ separate sources of light and separate light sensitive cells for the tracks so that one cell can deal with the low frequency side and the other with the high frequency side. It

is also known to employ a single source of light for two light sensitive cells connected to a common amplifier so that both cells have the same response but if one fails the other will enable the apparatus to continue. Still further it is also known to em ploy a common light source for two separate sound tracks and to split the light into two pencils by means of prisms so that two separate amplifiers are employed each hav- 0 ing its own thermionic circuit. The object of my present invention is to simplify sound reproduction and the invention is characterized by a common source of light for two light sensitive cells and means between 2 the sound track and the light sensitive cells for dividing the light into two zones so that the same image is directed on to both light sensitive cells each cell being connected to a separate loud speaker through its own thermionic circuit, the loud speaker appropriate to one cell however being tuned to respond to high frequency notes, and the other to low frequency notes.

My invention will be more clearly understood by reference to the accompanying diagram in which a selenium celll is separated from a photoelectric cell 2 by a thin opaque partition 3 having a knife edge 4. The selenium cell 1 is connected to its own loud speaker 5 through its own thermionic circuit 6, the loud speaker 5 being tuned to respond to high frequency notes. The photo-electric cell is connected to its own loud speaker 7 through its own thermionic circuit 8, this loud speaker 7 being tuned to respond to low frequency notes.

The film is indicated by the reference numeral 9 and its sound track area by its reference numeral 10. A small aperture 11 in a suitable box 12 is in juxtaposition to the aperture 11.

By means of the present invention full range of sounds as recorded on a single sound track are reproduced as there is no necessity as at present with single sound track an amplifier circuits to strike a medium between high and low frequency sounds.

; rate loud speaker through its own thermionic circuit the loud speaker appropriate to one cell being tuned to respond to high frequency notes and the other to low frequency notes.

In Witness hereof I have signed this specification.

FRANCIS DEANE. 

